Comparative Transcriptome Profile between Iberian Pig Varieties Provides New Insights into Their Distinct Fat Deposition and Fatty Acids Content

Abstract

[EN] Iberian pigs are meat quality models due to their high fat content, high intramuscular fat, and oleic fatty acid composition. These parameters present great variability and are differentiated among the lines that make up the Iberian pig population. However, there is little information on how the genetic expression influences quality across Iberian varieties. This study aimed to compare the muscle expression profile between two varieties of Iberian pig (Torbiscal and Retinto) and their reciprocal crosses, differentiated by fatness. Our results suggest that the Retinto variety, which has the greatest fat content amongst the studied Iberian varieties, showed a higher expression of genes related to adiposity. Likewise, a higher expression of genes related to lipolysis was found in the Torbiscal variety, described as having less fat content than Retinto. Further genetic variation analysis in these Iberian varieties showed relevant associations for SNP (Single Nucleotide Polymorphism), related to these differentially expressed genes, with the meat quality traits. Thus, our findings evidence that differences in the genetic architecture and expression of Iberian varieties might explain the variability in their fat content and composition and hence, their meat quality.

The high deposition of intramuscular fat and the content of oleic fatty acid are characteristic of the Iberian pig. These two parameters present great variability and are differentiated amongst the varieties that make up the Iberian pig population. Although previous studies generated evidence for causal genes and polymorphisms associated to the adipogenic potential of the Iberian pig, there is little information about how genetic expression influences this trait's variability. The aim of this study was to analyses the expression profile between two varieties of Iberian pig (Torbiscal and Retinto) and their reciprocal crosses differentiated in their intramuscular fat (IMF) content and fatty acid (FA) composition in the Longissimus thoracis muscle using an RNA-seq approach. Our results corroborate that the Retinto variety is the fattiest amongst all studied varieties as its upregulated genes, such as FABP3 and FABP5, SLC27A1 and VEGFA among others, contribute to increasing adiposity. In its turn, Torbiscal pigs showed an upregulation of genes associated with the inhibition of fat deposition such as ADIPOQ and CPT1A. Further genetic variation analysis in these Iberian varieties showed relevant associations for SNP located within the differentially expressed genes with IMF and FA content. Thus, the differences found in the genetic architecture and the muscle transcriptome of these Iberian varieties might explain the variability in their fat content and composition and hence, their meat quality.